
#include "type.h"
#include "const.h"
#include "protect.h"
#include "proto.h"
#include "proc.h"
#include "global.h"

PRIVATE void init_idt_desc(unsigned char vector, u8 desc_type, int_handler handler, unsigned char privilege);
PRIVATE void init_descriptor(DESCRIPTOR * p_desc, u32 base, u32 limit, u16 attribute);

/* 中断处理函数 */
void	divide_error();
void	single_step_exception();
void	nmi();
void	breakpoint_exception();
void	overflow();
void	bounds_check();
void	inval_opcode();
void	copr_not_available();
void	double_fault();
void	copr_seg_overrun();
void	inval_tss();
void	segment_not_present();
void	stack_exception();
void	general_protection();
void	page_fault();
void	copr_error();

void    hwint00();
void    hwint01();
void    hwint02();
void    hwint03();
void    hwint04();
void    hwint05();
void    hwint06();
void    hwint07();
void    hwint08();
void    hwint09();
void    hwint10();
void    hwint11();
void    hwint12();
void    hwint13();
void    hwint14();
void    hwint15();

/**
 * 初始化 386 中断门
 */
PRIVATE void init_idt_desc(unsigned char vector, u8 desc_type, int_handler handler, unsigned char privilege) {
    GATE * p_gate = &idt[vector];
    u32 base = (u32) handler;
    p_gate -> offset_low = base & 0xFFFF;
    p_gate -> selector = SELECTOR_KERNEL_CS;
    p_gate -> dcount = desc_type | (privilege << 5);
    p_gate -> attr = desc_type | (privilege << 5);
    p_gate -> offset_high = (base >> 16) & 0xFFFF;
}

PUBLIC void init_prot() {

	init_8259A();

	// 全部初始化成中断门(没有陷阱门)
	init_idt_desc(INT_VECTOR_DIVIDE,        DA_386IGate, divide_error,              PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_DEBUG,         DA_386IGate, single_step_exception,     PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_NMI,           DA_386IGate, nmi,                       PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_BREAKPOINT,    DA_386IGate, breakpoint_exception,	    PRIVILEGE_USER);
	init_idt_desc(INT_VECTOR_OVERFLOW,      DA_386IGate, overflow,                  PRIVILEGE_USER);
	init_idt_desc(INT_VECTOR_BOUNDS,        DA_386IGate, bounds_check,              PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_INVAL_OP,      DA_386IGate, inval_opcode,              PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_COPROC_NOT,    DA_386IGate, copr_not_available,        PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_DOUBLE_FAULT,  DA_386IGate, double_fault,              PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_COPROC_SEG,    DA_386IGate, copr_seg_overrun,          PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_INVAL_TSS,     DA_386IGate, inval_tss,                 PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_SEG_NOT,       DA_386IGate, segment_not_present,       PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_STACK_FAULT,   DA_386IGate, stack_exception,           PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_PROTECTION,    DA_386IGate, general_protection,        PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_PAGE_FAULT,    DA_386IGate, page_fault,                PRIVILEGE_KRNL);
	init_idt_desc(INT_VECTOR_COPROC_ERR,    DA_386IGate, copr_error,                PRIVILEGE_KRNL);

    // ===
    
    init_idt_desc(INT_VECTOR_IRQ0 + 0, DA_386IGate, hwint00, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ0 + 1, DA_386IGate, hwint01, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ0 + 2, DA_386IGate, hwint02, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ0 + 3, DA_386IGate, hwint03, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ0 + 4, DA_386IGate, hwint04, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ0 + 5, DA_386IGate, hwint05, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ0 + 6, DA_386IGate, hwint06, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ0 + 7, DA_386IGate, hwint07, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ8 + 0, DA_386IGate, hwint08, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ8 + 1, DA_386IGate, hwint09, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ8 + 2, DA_386IGate, hwint10, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ8 + 3, DA_386IGate, hwint11, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ8 + 4, DA_386IGate, hwint12, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ8 + 5, DA_386IGate, hwint13, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ8 + 6, DA_386IGate, hwint14, PRIVILEGE_KRNL);
    init_idt_desc(INT_VECTOR_IRQ8 + 7, DA_386IGate, hwint15, PRIVILEGE_KRNL);

    // ===
    // 初始化系统调用的中断门
	init_idt_desc(INT_VECTOR_SYS_CALL,    DA_386IGate, sys_call,                PRIVILEGE_USER);

    // 准备 GDT 和 TSS
    memset(&tss, 0, sizeof(tss));
    tss.ss0 = SELECTOR_KERNEL_DS;
    init_descriptor(&gdt[INDEX_TSS], vir2phys(seg2phys(SELECTOR_KERNEL_DS), &tss), sizeof(tss) - 1, DA_386TSS);
    tss.iobase = sizeof(tss);

    int i;
    PROCESS* p_proc = proc_table;
    u16 selector_ldt = INDEX_LDT_FIRST << 3;

    // 填充 GDT 中进程的 LDT 的描述符
    for(i = 0; i < NR_TASKS; i++) {
        init_descriptor(&gdt[selector_ldt >> 3], 
                        vir2phys(seg2phys(SELECTOR_KERNEL_DS), proc_table[i].ldts), 
                        LDT_SIZE * sizeof(DESCRIPTOR) - 1, 
                        DA_LDT);
        p_proc++;
        selector_ldt += 1 << 3;
    }
}

/**
 * 异常处理
 */
PUBLIC void exception_handler(int vec_no,int err_code,int eip,int cs,int eflags) {
	int i;
	int text_color = 0x74; /* 灰底红字 */

    // 异常信息
	char * err_msg[] = {"#DE Divide Error",
			    "#DB RESERVED",
			    "--  NMI Interrupt",
			    "#BP Breakpoint",
			    "#OF Overflow",
			    "#BR BOUND Range Exceeded",
			    "#UD Invalid Opcode (Undefined Opcode)",
			    "#NM Device Not Available (No Math Coprocessor)",
			    "#DF Double Fault",
			    "    Coprocessor Segment Overrun (reserved)",
			    "#TS Invalid TSS",
			    "#NP Segment Not Present",
			    "#SS Stack-Segment Fault",
			    "#GP General Protection",
			    "#PF Page Fault",
			    "--  (Intel reserved. Do not use.)",
			    "#MF x87 FPU Floating-Point Error (Math Fault)",
			    "#AC Alignment Check",
			    "#MC Machine Check",
			    "#XF SIMD Floating-Point Exception"
	};

	/* 通过打印空格的方式清空屏幕的前五行，并把 disp_pos 清零 */
	disp_pos = 0;
	for(i=0;i<80*5;i++){
		disp_str(" ");
	}
	disp_pos = 0;

	disp_color_str("Exception! --> ", text_color);
	disp_color_str(err_msg[vec_no], text_color);
	disp_color_str("\n\n", text_color);
	disp_color_str("EFLAGS:", text_color);
	disp_int(eflags);
	disp_color_str("CS:", text_color);
	disp_int(cs);
	disp_color_str("EIP:", text_color);
	disp_int(eip);

	if(err_code != 0xFFFFFFFF){
		disp_color_str("Error code:", text_color);
		disp_int(err_code);
	}
}

// 根据段名(即段选择子)转32位段基地址
PUBLIC u32 seg2phys(u16 seg) {
    // 根据描述符索引去 GDT 寻找对应的描述符
    DESCRIPTOR* p_dest = &gdt[seg >> 3]; 
    // 将描述符中分开的三个基地址拼凑成一个完整的段基地址
    return (p_dest -> base_high << 24 | p_dest -> base_mid << 16 | p_dest -> base_low);
}

// 初始化段描述符
PRIVATE void init_descriptor(DESCRIPTOR* p_desc, u32 base, u32 limit, u16 attribute) {
    p_desc -> limit_low         = limit & 0x0FFFF;
    p_desc -> base_low          = base & 0x0FFFF;
    p_desc -> base_mid          = (base >> 16) & 0x0FF;
    p_desc -> attr1             = attribute & 0xFF;
    p_desc -> limit_high_attr2  = ((limit >> 16) & 0x0F) | (attribute >> 8) & 0xF0;
    p_desc -> base_high         = (base >> 24) & 0x0FF;
}
